Single revolution clutch with auto-homing feature

Abstract

A single revolution clutch with an auto-home feature. This feature, added to the single revolution clutch, provides a mechanical home position stop. It utilizes the motion of the case to accomplish this. Whenever the clutch is energized, the case is pulled in, or the 1 mm gap is closed. The control ring has an additional single home detent on the opposite side to the one or more detents normally found on the single revolution clutch. The case has a tab feature, which can be punched out of the case itself, or can be tacked on as an additional piece of metal or plastic. This tab feature, seen as an "L" shape from the side, will move with the case. When the case is energized and closes its 1 mm gap, the normal detents on both the control ring and the case, spin free of each other. However, the "L" tab now moves closer to the single home tab on the other side of the control ring, and locks the control ring within one revolution of rotation or less. In this manner, the home position of the shaft is automatically located. When the case is released when the clutch is de-energized, the case moves out and the control ring rotates until the nearest detent locks with the normal detent on the case. The clutch continues operation in the normal manner, ie. pulsing periodically to move to the next shaft position, and so on.

We claim: 
     
       1. An indexing clutch having an auto home position feature comprising: an input member;   an output member;   an engagement device to selectively connect said input member and said output member;   a control member, said control member having an indexing protrusion located thereon that is engageable by said engagement device, and a home indexing protrusion located thereon on a side opposite said indexing protrusion, wherein said home indexing protrusion is engaged upon disengagement of said engagement device to position said output member at a desired location;   an actuator to selectively engage said engagement device;   a locator for mechanically positioning said control member in a home position after disengagement of said engagement device.   
     
     
       2. A clutch according to claim 1 further comprising a plurality of indexing protrusions located on said control member. 
     
     
       3. A clutch according to claim 1 wherein said input member comprises: a gear; and   a shaft attached to said gear.   
     
     
       4. A clutch according to claim 1 wherein said engagement device comprises: a backing member;   an electromagnet; and   a ferromagnetic body adjacent said electromagnet, wherein upon actuation of said actuator said electromagnet causes said ferromagnetic body to be drawn toward said backing member.   
     
     
       5. A clutch according to claim 4 further comprising a biasing member located between said backing member and said ferromagnetic body to return the body to a disengaged position upon disactuating of said actuator. 
     
     
       6. A device having an indexing drive including a clutch, comprising: an input member;   an output member;   an engagement device to selectively connect said input member and said output member;   a control member, said control member having an indexing protrusion located thereon that is engageable by said engagement device, and a home indexing protrusion located thereon on a side opposite said indexing protrusion, wherein said home indexing protrusion is engaged upon disengagement of said engagement device to position said output member at a desired location;   an actuator to selectively engage said engagement device;   a locator for mechanically positioning said control member in a home position after disengagement of said engagement device.   
     
     
       7. A clutch according to claim 6 further comprising a plurality of indexing protrusions located on said control member. 
     
     
       8. A clutch according to claim 6 wherein said input member comprises: a gear; and   a shaft attached to said gear.   
     
     
       9. A clutch according to claim 6 wherein said engagement device comprises: a backing member;   an electromagnet; and   a ferromagnetic body adjacent said electromagnet, wherein upon actuation of said actuator said electromagnet causes said ferromagnetic body to be drawn toward said backing member.   
     
     
       10. A clutch according to claim 9 further comprising a biasing member located between said backing member and said ferromagnetic body to return the body to a disengaged position upon disactuating of said actuator. 
     
     
       11. An electrophotographic printing machine having a cleaning device that is selectively disengageable from a photoreceptive member, comprising: a cylindrical cleaning brush;   an elongated member rotatably supporting said cylindrical cleaning brush at one end thereof;   a follower member, located on the opposite end of said elongated member; said elongated member being pivotably mounted between said cleaning brush and said follower member;   a cam rotatably supported wherein said follower member is biased against said cam so that rotation of said cam causes said cleaning brush to be selectably contacted with and removed from a photoreceptive member;   a drive system including an indexing clutch for driving said cam, wherein said drive system comprises: an input member;   an output member;   an engagement device to selectively connect said input member and said output member;   a control member, said control member having an indexing protrusion located thereon that is engageable by said engagement device, and a home indexing protrusion located thereon on a side opposite said indexing protrusion, wherein said home indexing protrusion is engaged upon disengagement of said engagement device to position said output member at a desired location;   an actuator to selectively engage said engagement device;   a locator for mechanically positioning said control member in a home position after disengagement of said engagement device.     
     
     
       12. A printing machine according to claim 11 further comprising a plurality of indexing protrusions located on said control member. 
     
     
       13. A printing machine according to claim 11 wherein said input member comprises: a gear; and   a shaft attached to said gear.   
     
     
       14. A printing machine according to claim 11 wherein said engagement device comprises: a backing member;   an electromagnet; and   a ferromagnetic body adjacent said electromagnet, wherein upon actuation of said actuator said electromagnet causes said ferromagnetic body to be drawn toward said backing member.   
     
     
       15. A printing machine according to claim 14 further comprising a biasing member located between said backing member and said ferromagnetic body to return the body to a disengaged position upon disactuating of said actuator.